servo/components/gfx/display_list/optimizer.rs
Manish Goregaokar ea9842723d Audit and reduce unstable usage in gfx
Reasons behind existing unstable features:

alloc:

 - weak pointers (may not belong)
 - boxed::into_raw and from_raw (naming)

collections:

 - `Vec.push_all()` (May be replaced)
   - Replace with loop

core:

 - `min_by` (#15311)
 - `PI_2` (naming)

rustc_private:

 - FnVHasher
   - Can be replaced by rust-fnv

std_misc:

 - Hash state stuff (no option here unless we want to stop using it)

str_char:

 - CharRange usage
   - Can be replaced by regular iterators (char_indices)
2015-06-09 23:24:18 +05:30

70 lines
3.4 KiB
Rust

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Transforms a display list to produce a visually-equivalent, but cheaper-to-paint, one.
use display_list::{DisplayItem, DisplayList, StackingContext};
use std::collections::linked_list::LinkedList;
use geom::rect::Rect;
use util::geometry::{self, Au};
use std::sync::Arc;
/// Transforms a display list to produce a visually-equivalent, but cheaper-to-paint, one.
pub struct DisplayListOptimizer {
/// The visible rect in page coordinates.
visible_rect: Rect<Au>,
}
impl DisplayListOptimizer {
/// Creates a new display list optimizer object. `visible_rect` specifies the visible rect in
/// page coordinates.
pub fn new(visible_rect: &Rect<f32>) -> DisplayListOptimizer {
DisplayListOptimizer {
visible_rect: geometry::f32_rect_to_au_rect(*visible_rect),
}
}
/// Optimizes the given display list, returning an equivalent, but cheaper-to-paint, one.
pub fn optimize(self, display_list: &DisplayList) -> DisplayList {
let mut result = DisplayList::new();
self.add_in_bounds_display_items(&mut result.background_and_borders,
display_list.background_and_borders.iter());
self.add_in_bounds_display_items(&mut result.block_backgrounds_and_borders,
display_list.block_backgrounds_and_borders.iter());
self.add_in_bounds_display_items(&mut result.floats, display_list.floats.iter());
self.add_in_bounds_display_items(&mut result.content, display_list.content.iter());
self.add_in_bounds_display_items(&mut result.positioned_content,
display_list.positioned_content.iter());
self.add_in_bounds_display_items(&mut result.outlines, display_list.outlines.iter());
self.add_in_bounds_stacking_contexts(&mut result.children, display_list.children.iter());
result
}
/// Adds display items that intersect the visible rect to `result_list`.
fn add_in_bounds_display_items<'a,I>(&self,
result_list: &mut LinkedList<DisplayItem>,
display_items: I)
where I: Iterator<Item=&'a DisplayItem> {
for display_item in display_items {
if self.visible_rect.intersects(&display_item.base().bounds) &&
display_item.base().clip.might_intersect_rect(&self.visible_rect) {
result_list.push_back((*display_item).clone())
}
}
}
/// Adds child stacking contexts whose boundaries intersect the visible rect to `result_list`.
fn add_in_bounds_stacking_contexts<'a,I>(&self,
result_list: &mut LinkedList<Arc<StackingContext>>,
stacking_contexts: I)
where I: Iterator<Item=&'a Arc<StackingContext>> {
for stacking_context in stacking_contexts {
let overflow = stacking_context.overflow.translate(&stacking_context.bounds.origin);
if self.visible_rect.intersects(&overflow) {
result_list.push_back((*stacking_context).clone())
}
}
}
}